He said the samples of quartz came from the lowest deposit of the study area, and that the possible age range is broad. "I unfortunately don't share their conclusions that they have resolved the issue of timing of when people were making these footprints," he said. Loren Davis, a professor of anthropology at Oregon State University who co-authored the critical paper last year, said he thinks the new research is important, but not conclusive. "But it's the totality of the study, the congruence of the ages from all three different dating techniques, that really make our results exceptionally robust." "People can argue against any single dating technique," he said. Geological Survey, hopes this will close the case. Today, a new paper is out with the results, and the scientists say both sets of evidence align with the dates of their original findings. It looks at the luminescent properties of quartz crystals, which change with age. "They're like tubes pounded in the sedimentary sequence and taken back to a laboratory and analyzed," said Springer.įor those samples they used a different technique called optically stimulated luminescence. ![]() So, after some pandemic-related delays, the researchers returned to the excavation site, this time to carbon-date tree pollen, for better accuracy. But aquatic plants can absorb older carbon from water, skewing the results. Another paper published in Science said the dating technique used was flawed: The scientists had carbon-dated seeds from Ruppia cirrhosa, a grasslike aquatic plant that lives in lakes and that was embedded along with the footprints. The overlapping tracks – and timeline – of humans and megafauna also opened new questions about how long the species coexisted, and what role humans might or might not have played in their extinction.Ĭritics challenged the research. "It opens up whole avenues of migratory pathways," she said. But if her team's analysis of the footprints was correct, maybe that was wrong, and humans found a way onto the continent even when its northern lands were still ice-bound. ![]() She says scientists had thought humans might have crossed from what is now Siberia to Alaska toward the end of the last Ice Age. "These ages were really much older than the accepted paradigm of when humans entered North America," said Kathleen Springer, one of the US Geological Survey researchers who wrote the report. Geological Survey and others published a paper in the journal Science saying those footprints were between 21,000 and 23,000 years old. In 2021, researchers from the National Park Service, the U.S. That basin held a lake during the last Ice Age, and its dried-out banks preserve the prints. The footprints are among thousands made by humans, mammoths, giant sloths and others in White Sands National Park, an ethereal landscape in southern New Mexico where waves of white gypsum dunes lap across the vast Tularosa basin. How long have humans lived on the American continent?įor decades, one prevailing answer was perhaps 14,000 years, based largely on the age of early human stone tools known as Clovis points, first discovered in Clovis, NM.īut a new analysis of fossilized human footprints adds weight to the case for a longer human history in the Americas.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |